The original HL1 mod that spawned nearly a decade a fun before TF2 became, where grenade body flinging and gibbing was (or maybe still is) king.

Climb up the ranks in Competitive mode or play it simply in Casual mode

A fun hat simulator where you can fight other mercenaries (PvP) or fight off robots (PvE)

Play HL1 plus it's expansions with friends and experience the Half-Life universe cooperatively.

Fun Zombie Survival Game that it's in-built Director always changes up the variety of the game. Versus also pits players against infected players for more fun or bragging rights.